Low-frequency oscillations of shock wave/turbulent boundary layer interaction over a vibrating panel

This study employs direct numerical simulations to investigate the influence of a vibrating wall panel on the oblique shock wave/turbulent boundary layer interaction flows at incoming free-stream Mach number 2.9. We examine two distinct low-frequency vibration modes, defined by their streamwise deformation patterns: a full-panel (symmetric) mode and a half-panel (antisymmetric) mode. By analysing phase-average flow quantities, we demonstrate that the antisymmetric mode primarily forces a streamwise oscillation of the separation bubble, whereas the symmetric mode amplifies its inherent expansion–contraction (‘breathing’) motion. Both panel vibrating modes enhance quasi-periodic shock oscillation and modulate the plateau in the mean wall pressure distributions. Spectral analysis confirms that low-frequency pressure fluctuations are amplified not only at the mean separation point but also in the mid-region of the panel. Through correlation analysis and dynamic mode decomposition, we establish that these vibrations lead to strong spatiotemporal coherence, associating upstream fluctuations near the separation to downstream propagation. Critically, a comparative analysis reveals that the symmetric mode facilitates significantly longer downstream propagation of pressure disturbances than the antisymmetric mode. This highlights how the spatial pattern of panel deformation, not just the vibration frequency, modulates the unsteady flow characteristics.